The present invention is directed, in general, to wireless networks and, more specifically, to a system for preventing 911 emergency calls from being dropped due to sector wilting in a base station.
Wireless networks, and cellular telephone networks in particular, have become ubiquitous in society. Within the United States, cellular service is offered by cellular service providers, by the regional Bell companies, and by the national long distance operators. The enhanced competition has driven the price of cellular service down to the point where it is affordable to a large segment of the population.
One of the most important features of a wireless (or cellular) phone is its use in emergency situations. A wireless phone allows a subscriber to call for help nearly instantaneously from practically any location. Enhanced services in cellular phones may also allow a wireless network to remotely determine the location of a cellular telephone, thereby allowing police, firefighters and other emergency personnel to be sent to the location of the cellular phone.
However, certain maintenance procedures and emergency fault procedures may unintentionally cause an emergency call to be dropped as a result of xe2x80x9cwiltingxe2x80x9d a sector or even an entire base station. It is frequently necessary, for the purposes of routine maintenance and/or recovering from a critical fault, to reduce (i.e., to wilt) the power of one or more RF transmitters in a base station in a wireless network. The wilting may be done to a single sector in a multi-sector base station or it may be done to all sectors of the base station. Wilting a base station (or a sector) causes mobile stations that are in communication with the base station (or sector) to search for other base stations and eventually causes the mobile stations to be handed off to new base stations. If a new base station cannot be found in time, a call may be dropped due to the wilting. While this may be annoying for routine wireless telephone calls, dropping an emergency call may result in loss of life.
There is therefore a need in the art for improved wireless networks that are less susceptible to dropping emergency calls. In particular, there is a need for wireless networks that are less likely to drop emergency calls during routine maintenance or during critical failures in one or more sectors of a base station.
To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a wireless network comprising a plurality of base transceiver substations capable of communicating with a plurality of mobile stations, an apparatus for preventing the dropping of an emergency call associated with a first one of the plurality mobile stations. According to an advantageous embodiment of the present invention, the apparatus comprises a call drop controller capable of 1) receiving from the wireless network a maintenance command directed to a first base transceiver substation handling the emergency call, 2) determining whether the maintenance command is capable of causing the first base transceiver substation to drop the emergency call and, 3) in response to a determination that the maintenance command may cause the first base transceiver substation to drop the emergency call, preventing the maintenance command from being executed by the first base transceiver substation.
According to one embodiment of the present invention, the call drop controller, in response to a determination that the maintenance command will not cause the first base transceiver substation to drop the emergency call, allows the maintenance command to be executed by the first base transceiver substation.
According to another embodiment of the present invention, the call drop controller is further capable of determining whether a second base transceiver substation proximate to the first base transceiver substation is handling a second emergency call, and, in response to a determination that the second base transceiver is handling the second emergency call, preventing the maintenance command from being executed.
According to still another embodiment of the present invention, the call drop controller, in response to a determination that the second base transceiver is not handling the second emergency call, allows the maintenance command to be executed by the first base transceiver substation.
It is also a primary object of the present invention to provide, for use in a wireless network comprising a plurality of base transceiver substations capable of communicating with a plurality of mobile stations, an apparatus for preventing the dropping of an emergency call associated with a first one of the plurality mobile stations, wherein the apparatus comprises a call drop controller capable of receiving from the wireless network a maintenance command directed to a first base station controller, determining whether the maintenance command is capable of causing a first base transceiver substation controlled by the first base station controller to drop the emergency call, and, in response to a determination that the maintenance command may cause the first base transceiver substation to drop the emergency call, preventing the maintenance command from being executed by the first base station controller.
According to a further embodiment of the present invention, the call drop controller, in response to a determination that the maintenance command will not cause the first base transceiver substation to drop the emergency call, allows the maintenance command to be executed by the first base station controller.
According to a still further embodiment of the present invention, the call drop controller is further capable of determining whether a second base transceiver substation proximate to the first base transceiver substation is handling a second emergency call, and, in response to a determination that the second base transceiver is handling the second emergency call, preventing the maintenance command from being executed by the first base station controller.
According to a yet further embodiment of the present invention, the call drop controller, in response to a determination that the second base transceiver is not handling the second emergency call, allows the maintenance command to be executed by the first base transceiver substation.
Another object of the present invention to provide an apparatus that prevents emergency calls from being dropped when a base station resource fails in the wireless network. Accordingly, in an advantageous embodiment of the present invention, there is provided, for use in a wireless network comprising a plurality of base transceiver substations capable of communicating with a plurality of mobile stations, an apparatus for preventing the dropping of an emergency call associated with a first one of the plurality mobile stations, wherein the apparatus comprises a call drop controller capable of: 1) receiving a failure notification from a failed base transceiver substation, 2) determining whether the failed base transceiver substation is handling the emergency call and, 3) in response to a determination that the failed base transceiver substation is handling the emergency call, at least one of: a) increasing transmission power of at least one base transceiver substation proximate to the failed base transceiver substation; b) increasing a TDROP value of the failed base transceiver substation; and 3) decreasing a TADD value of at least one base transceiver substation proximate to the failed base transceiver substation.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprise,xe2x80x9d as well as derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9das well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontrollerxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.